Mechanical telephone



(No Model 0.- M. RADFORD.

MECHANIGAL TELEPHONE.

Patented Mar. 29

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CASSIUS M. RADFORD, OF CONCORD, NE\V HAMPSHIRE.

MECHANICAL TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 360,362, dated March 29, 1887.

Application filed August 31, 1886.

To aZZ whom it may concern.-

Be it known that I, CAssrUs M. RADFORD, a citizen of the United States, residing at Concord, in the county'of Merrimac and State of New Hampshire, have invented certain new and useful Improvements in Mechanical Telephones; and I do hereby declare that the following is a full and exact description thereof, reference being had to the accompanying drawings, making part of this specification.

The object of this invention is to increase the vibrating power of the telephone in the direction of the line-wire, thereby making the instrument available for use on longer distance lines; to overcomethe lateral vibration, and consequently to do away with the ringing sound common to mechanical telephones as previously constructed, and to secure a more perfect articulation, in order that conversation may be carried on more rapidly and still be perfectly distinct.

The nature of the invention consists in the general and specific features of construction and arrangement hereinafter set forth and claimed.

The invention is illustrated in the accompanying drawings, in which- Figure 1 represents a front view of the telephone. Fig. 2 is a view in the same direction, showing the parts underneath the diaphragmplate, the diaphragm-plate being removed; and Fig. 3 is a central vertical section of the instrument, taken from front to back of the instrument.

Like letters designate corresponding parts v in all the figures.

A is the diaphragm, of parchment or any suitable material, attached to the diaphragmplate a in any convenient manner. Through the center of the diaphragm the line-wire 13 passes and terminates in a bottom, b, by means of which the wire is held in connection with the diaphragm; A little distance back of the diaphragm-plate, and similar thereto, is a second plate, 0, retained in positionby four posts, d d, secured to the back of the telephone. To this plate, across the central circular aperture therein, are fastened two tightly-drawn crossstraps, D D, preferably of rawhide or similar material, crossing each other in the center of the circular aperture and just back of the cen- Serial No. 212.312. (No mcdi-l.)

ter of the diaphragm. Upon the frontside of these straps, at their point of intersection, the diaphrngnrcushion O, of cork or rubber, isfastened. The cushion-plate is fixed at such adistance from the diaphragm-plate, and consequently'the cushion at such a distance from the diaphragm, that when the latter is drawn down to the proper tension by means of the line-wire and the button on the end of the linewire it will be firmly held against the cushion 0, thereby rendering the diaphragm more firm and assisting to prevent lateral vibration. The cushion C may be more firmly'held in position and its functions materially assisted by a second set of cross-straps, E E, preferably of silk or similar material, crossing each other in front of and drawn tightly against the cushion, and attached to the same plate as the straps D D.

Just in rear of the cusl1iou-plate,and near the the back of the telephone, is fixed asecondary diaphragm, F, as shown in Fig. 3. This diaphragm may be made of canvas or any convenient or suitable material. On the back side of the cross-straps D D,opposite thecushion 0, a cylindrical piece of cork or rubber, G, is fastened, which, for convenience, I call a vibrator, and is so arranged as to be close to but not in contact with the secondary diaphragm F. \Vhen the diaphragm A is vibrated, as when the telephone is in operation, the Vibrations of the diaphragm A are transmitted through the cushion O to the vibrator G, which is thereby caused to strike against the secondary diaphragm F, and thus the strength of the vibration in the direction of the line-wire is greatlyincreased.

The line-wire passes from the diaphragm A through cushion O, straps D D and E E, vibrator G, and secondary diaphragm F, and thus is in continuous connection with the vibrating medium throughout nearly the whole depth of the telephone. The metallic ringing sound that usually accompanies conversation by means of telephones of this class is thus greatly lessened or entirely obviated, and the Whole strength of the vibration is confined to and transmitted by the line-wire.

The secondary diaphragm F is supported in any convenient manner, the means showna circular frame of any convenient size and thickness fastened to the back of the instrumentbeing an efficient and inexpensive method.

For the purpose of increasing the strength of the vibrations, the diaphragm-plate a is mounted upon cushions H H, of elastic material, as cork or rubber, as shown in Fig. 3,the cushions being of sufficient thickness to retain the diaphragrn- 'ilate at the proper distance from the cushion-plate 0. These cushions H H may be placed one at each corner of the plate.

The frame-work in which the mechanism is contained may be of any desired form, a rectangular box of wood being well adapted to the purpose. A rubber block, I, is attached to the back of the telephone, through which the line-wire passes, thus preventing the line-wire from coming in contact with the wood-work of the instrument and confusing the vibrations.

Telephones of this construction are made at a very small cost, and are found to answer the purposes for which this class of instrument is ordinarily used much better than those of any other construction. It is shown by actual test that the lateral vibration is practically overcome, the ringing noise is obviated, and the vibrations are stronger and transmitted more directly in the direction of the line-wire, and are thus capable of being transmitted to a greater distance and with more perfect articulation than with anyinstrument heretofore in use.

I claim as my invention 1. In a mechanical telephone, the combination ot'the diaphragm A, line-wire B, and cushion O, attached to and supported by the cross straps D D and E E, substantially as and for the purpose herein specified.

2. In a mechanical telephone, the combina tion of the diaphragm A, line-wire B, cushion O, resting against andsupported by the cross straps D D, and cross straps E E, crossing in front of and in frictional contact with the said cushion, substantially as and for the purpose herein specified.

3. In a mechanical telephone, the combination of the diaphragm A, line-wire B, and cushion 0 with the secondary diaphragm F and vibrator G, substantially as and for the purpose herein specified.

4. In a mechanical telephone,the diaphragm A and 1ine-wire B, in combination with the diaphragm-cushion 0, supported and retained in position by two sets of cross-straps, D D and E E, one set crossing behind the said cushion and the other set crossing in front of the said cushion, vibrator attached to the straps D D at their intersection and on the opposite side of the straps from cushion O, and the secondary diaphragm F, the vibrator being held close to but not in contact with the secondary dia phragm, substantially as specified, whereby the vibrator strikes against the secondary diaphragm when the diaphragm A is vibrated.

5. In a mechanical telephone, thelinewvire B and diaphragm A, in combination with cushion O, vibrator G, and secondary diaphragm F, the line-wire passing through the cushion, vibrator, and secondary diaphragm, as and for the purpose herein specified, whereby the line- Wire has continuous connection with the vibrating parts of the instrument.

6. In a mechanical telephone,the diaphragm A and line-wire B, in combination with the diaphragm -cushion C and diaphragm-plate cushion or cushions H H, substantially as and for the purpose herein specified.

In testimony whereof I have hereunto sulr scribed my name in the presence of two witnesses.

OASSIUS M. RADFORD.

XVitnesses:

J. F. Ronnn'rsoN, NATHANIEL E. hIAR'IIN. 

